Obesity is one of the most prevalent and challenging public health issues of our time. In November 2011, the Centers for Medicare and Medicaid Services (CMS) approved the use of a new Healthcare Common Procedure Coding System (HCPCS) code for payment in primary care for providing Intensive Behavioral Therapy (IBT) treatment for obese patients. Despite the widespread prevalence of obesity in the Medicare population, use of this benefit has been substantially lower than expected suggesting significant underutilization of this benefit. This exploratory study will pursue the following aims: 1) To develop a thorough understanding of the most pressing issues related to the use and non-use of the Medicare IBT for obesity benefit in primary care, and 2) To study the strategies used in practices that have successfully implemented services in accordance with the IBT for obesity Medicare benefit and describe: a) characteristics of these practices and their environmental context, b) key elements of the implementation process that facilitate successful in-practice intervention, c) patients use of the IBT for obesity benefit, including continuing receipt of services after meeting the weight loss requirement of the benefit, and d) cost to provide the service relative to the reimbursement amount. To accomplish aim 1, we will query the Medicare Provider Utilization and Payment Data: Physician and Other Supplier database for three states: Colorado, Michigan, and North Carolina and identify all providers and their practices that have been paid by Medicare for delivering IBT for obesity services to 10 or more beneficiaries in a year between 2012 and 2014. We will identify the primary care practices of these providers and conduct semi-structured telephone interviews with the universe of practices (up to 100 total). We will then identify practices that are not using the IBT benefit, matched on zip code, practice size (>5 providers), and family or internal medicine to practices using the benefit and conduct similar interviews with this group. Interviews will assess practice characteristics, reasons for use, non-use and stopping use of the benefit, processes and personnel involved, and any known patient results. To accomplish aim 2, we will purposefully select 36 practices from aim 1 that meet our criteria for IBT for obesity implementation success to collect in- depth information to understand their implementation, patient outcomes and costs. Data gathering will include on-site interviews and observations, and EMR data extraction. Normalization process theory will be used to understand factors important to implementation. These methods will also be used to obtain information to estimate the cost to the practice of providing IBT services and assess its sustainability under current and alternative reimbursement amounts. Our findings have direct policy implications informing the dissemination and sustainability of effective implementation strategies that can be learned from practices continuing to deliver IBT for obesity services. This study will add to the field by determining the use of this benefit, reasons for use and discontinuation of use, and identify potential strategies for effective implementation of IBT in primary care.